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  • Amp head > 8, or 16 ohms.

    Hi chaps, another basic amp question from me Im afraid.

    What is, or what would be the difference between an amp head -with two output ports, 8, & 16 ohms- going into an 8 ohm speaker ( using the 8 ohm port), vs a 16 ohm speaker ( going into the 16 ohm port) ? And if its a 35 watt amp, does that make any difference/ is that relevant?

    I mean amp characterists. What would I, as a player, hear. The exact same? Half the volume? Twice the volume? Any difference(s) at all ?

    Apart from dividing two 16 ohm speakers, to make an 8 ohm load ( if an amp only has on 8 ohm port that is ), by putting them in series ( iirc, or parralel).. I just don't undertsand this different ohms thing with speakers. (Why aren't they all the same? Or rather i mean why shouldn't they be all the same?)

    I mean why an amp would even have two different ports, like my eg, if you can " make" whatever the amp should have if it has just a sole one, by putting two speakers in series or paralleling two.. I cant understand either.

    Thanks. SC

  • #2
    They aren't all the same impedance so they can make combinations work out to reasonable impedances.

    When the amp has switchable output, running the amp into the appropriate load should equal out all the major differences, So 4 ohm out into 4 ohm cab is pretty much the same as 16 ohm out into 16 ohm cab.
    There are some slight variations such as the weight of the speaker voice coil, but they are very subtle differences.
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #3
      Originally posted by g1 View Post
      They aren't all the same impedance so they can make combinations work out to reasonable impedances.

      When the amp has switchable output, running the amp into the appropriate load should equal out all the major differences, So 4 ohm out into 4 ohm cab is pretty much the same as 16 ohm out into 16 ohm cab.
      There are some slight variations such as the weight of the speaker voice coil, but they are very subtle differences.
      Aha good ok thanks g1. So for eg, a vox ac30 dimed.. will sound no different with an 8 ohm load, as a 16 ohm load?

      I had in mind you see bidding on a ac30 clone head ( proper orig circuit) which had both 8 & 16 ohm outputs. And I have this unused 30w vintage celestion 16 ohm grey back I could've made an extention cabinet with. But the damn amp listing has been pulled, 1 bidder must have offered £800 which is what the seller told me he wanted for it.

      Anyway thanks, useful to have a bit more knowledge. S C

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      • #4
        Lots of videos on YouTube where they compare the same speaker but of different impedance. Put on some headphones and see if you can hear the difference.

        Speakers comparison, 8 ohm vs 16 ohm - Crunch

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        • #5
          Hey hears an analogy for ya.....

          My car sounds different when I try to run around town in first gear. Thoughts on that could be more wear and tear on the engine and transmission .

          My amp sounds different when I run the wrong impedance tap on my amp.. Thoughts on that more wear and tear on tubes and transformers.

          nosaj
          soldering stuff that's broken, breaking stuff that works, Yeah!

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          • #6
            From what I read, the question was about when the amp was properly matched to the load using the appropriate switch setting or jack.
            Of course if you mismatch amp to load, there will be tonal differences in the sound. That is a different question.
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


            Comment


            • #7
              Originally posted by Sea Chief View Post
              will sound no different with an 8 ohm load, as a 16 ohm load?.
              Your question is incomplete.
              will sound no different with an 8 ohm load, as a 16 ohm load? USING WHICH TAP?
              I had in mind you see bidding on a ac30 clone head ( proper orig circuit) which had both 8 & 16 ohm outputs. And I have this unused 30w vintage celestion 16 ohm grey back I could've made an extention cabinet with.
              Which exact model?
              Is it specc´d 30W?
              IF so , and it´s an old model, you will blow it when you dime your 30W amp.

              Not nitpicking: A 30W vintage Celestion (say a G12H) is a description and that speaker stands 30W RMS
              A Vintage 30 Celestion is a specific model name and stands 60W RMS (some variants 80 and even 90W RMS).

              Greenback/Blackback/Creamback/polka dot back mean nothing, those cover colours were used at random in the past and users think them important.
              So much so that NOW Celestion had to bow to marketing dept demands, which is nonsense.
              Juan Manuel Fahey

              Comment


              • #8
                Originally posted by TomCarlos View Post
                Lots of videos on YouTube where they compare the same speaker but of different impedance. Put on some headphones and see if you can hear the difference.

                Speakers comparison, 8 ohm vs 16 ohm - Crunch
                Hi Tom. Thanks for this, but it doesn't state if the two different speakers are going into the same output/ port/ socket whatever its called.. or if they're going into their corresponding numbered one.

                It could be of help as its general finding does correspond, perhaps ( though after 38 yrs playing electrics, I still have no idea what a 'scooped' sound possibly is.. so Im perhaps not the best judge) with my thinking my 16 ohm celestion was less bassy than what Im used to ( invariably modern std speakers, 8 ohms).

                But this was both into the same amps 8 ohm output hole.. as it had only one. Or it might have had an extra 4 ohm one, for what conceivable reason I have no idea, but I think this wasn't the best idea to use with the 16 ohm speaker. So I have no idea if the mismatch introduced this 'less bass' aspect, or, if the speaker just happened fo be less bassy, or, if the general characteristic of a 16 ohm spkr versus an 8 ohm one - is- as the clip perhaps suggests, that it is less bassy.

                If so, then this has been a useful exercise, as I loathe every speaker Ive ever had ( all 8 ohms as seems to be the 'usual one'.. for what reason, again I have no idea) due to the excessive bass they seemed to just inherrantly have. And I can think of now using my unused 16 ohm one. But in what config/ how.. is not exactly clear.

                I absolutely hate this speaker ohms difference thing. Drives me fkn nuts!

                Thanks SC

                Comment


                • #9
                  As usual, you manage to write a mid sized post without answering questions just above it.
                  Yet somehow expect answers ???????

                  Please answer post #7 in full.

                  Now I add: how many output "holes" does your amp have and what are they labelled?

                  Your post #1
                  -with two output ports, 8, & 16 ohms
                  contradicts post #8
                  the same amps 8 ohm output hole.. as it had only one. Or it might have had an extra 4 ohm one,
                  WTF???
                  Easy to do.
                  Juan Manuel Fahey

                  Comment


                  • #10
                    To be fair, I recall that Sea Chief had / has a 135W twin reverb, which have a hidden 8ohm output, unlabelled but accessible via switching contacts on the ext speaker jack.
                    My band:- http://www.youtube.com/user/RedwingBand

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                    • #11
                      Originally posted by J M Fahey View Post
                      As usual, you manage to write a mid sized post without answering questions just above it.
                      Yet somehow expect answers ???????

                      Please answer post #7 in full.

                      Now I add: how many output "holes" does your amp have and what are they labelled?

                      Your post #1 contradicts post #8 WTF???
                      Easy to do.
                      The 1 st line of post 1 it asks what would the difference be between:

                      "an amp head -with two output ports, 8, & 16 ohms- going into an 8 ohm speaker ( using the 8 ohm port), vs a 16 ohm speaker ( going into the 16 ohm port) ?

                      I couldn't possibly be any clearer as to what this amp has for its outputs, or, which port is used with which speaker JMF.

                      ---

                      And #8 doesn't contradict #1. As they are relevant to two completely different amps; post 1 is obviously relevant to mine. Post 8 is addressing Tom's clip, in which someone else's amp features ( the only one.. the only one.. whereby said amp's output, or outputs are unknown/ not clearly noted. As mine was ).

                      Your questions, & anger too, are the ones that make no sense.

                      SC.



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                      • #12
                        Originally posted by pdf64 View Post
                        To be fair, I recall that Sea Chief had / has a 135W twin reverb, which have a hidden 8ohm output, unlabelled but accessible via switching contacts on the ext speaker jack.
                        Hi pdf. I didn't know this, nor understand the relevance.

                        I'm only asking about a 35w head with two outputs.

                        Are you assuming maybe I have just missed the 1 from the front of 35w?
                        And also assuming I have mistaken a head, for a huge beast of a combo?

                        Thanks. SC

                        Comment


                        • #13
                          Originally posted by g1 View Post
                          From what I read, the question was about when the amp was properly matched to the load using the appropriate switch setting or jack.
                          Of course if you mismatch amp to load, there will be tonal differences in the sound. That is a different question.
                          g1 simply reads what I wrote.

                          Apologies Ive just seen JMF might have english as a 2nd language; in which case my posts could be construed as a bit complicated, & bits mistaken for contradiction. Understood.

                          But as g1 succinctly sums up here, post 1 is clear.

                          SC

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                          • #14
                            Originally posted by Sea Chief View Post
                            What is, or what would be the difference between an amp head -with two output ports, 8, & 16 ohms- going into an 8 ohm speaker ( using the 8 ohm port), vs a 16 ohm speaker ( going into the 16 ohm port) ? And if its a 35 watt amp, does that make any difference/ is that relevant?
                            Connecting an 8 Ohm speaker to the 8 Ohm output or connecting a 16 speaker to the 16 Ohm output doesn't make a difference to the amp.
                            It will produce the same output and sound (provided the speakers sound the same).

                            Reason is that by OT transformer action the power tubes see the same load in both cases.
                            Last edited by Helmholtz; 01-14-2022, 09:52 PM.
                            - Own Opinions Only -

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                            • #15
                              Originally posted by Helmholtz View Post

                              Connecting an 8 Ohm speaker to the 8 Ohm output or connecting a 16 speaker to the 16 Ohm output doean't make a difference to the amp.
                              It will produce the same output and sound (provided the speakers sound the same).

                              Reason is that by OT transformer action the power tubes see the same load in both cases.
                              Hi HH. That's great thanks. So the only thing different, if the amp is the same using either OT winding 8 or 16, is the corresponding speaker.

                              If one speaker has a number that is double the other, then I was wondering if the voice coil was double the wire thickness, or I dont know cone thickness double ( wild guess but you get the idea ), or double the number of coils around the centrepiece thing. In which case, I would think there had to be a significant difference.

                              But thats just my logic going too far then is it?

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